Specific binding of 125I-MCP-1 and125I-RANTES to monocytes/macrophages at different stages of differentiation. Cells from 4 different donors (1 × 106) were incubated with 0.25 nmol/L 125I-MCP-1 (A) or 0.1 nmol/L 125I-RANTES (B). After incubation for 2 hours at 4°C, cell pellets were extensively washed and the radioactivity was measured in a γ counter. Specific binding was defined as the differences between total binding and nonspecific binding in the presence of a 200-fold excess of unlabeled chemokines; nonspecific binding never exceeded 20% of total binding. Each point represents the average of duplicate measurements. Statistical analysis showed that the differences in the binding of MCP-1 and RANTES observed in monocytes at different stages of differentiation were statistically significant (1-way analysis of variance P = .009 for MCP-1 and P= .0397 for RANTES; Kruskall-Wallis test P = .0125 for MCP-1 and P = .0097 for RANTES).
